Method for rolling Z-section sheet piles

Abstract

A method is presented for hot rolling a Z-section sheet pile from a semi-finished H-beam. The semi-finished H-beam is oriented in such a way that its web is substantially parallel to a rolling plane. A preform of the sheet pile is first rolled in a first plurality of rolling passes to form a preform having two flange/web transition sections substantially parallel to the rolling plane. These two flange/web transition sections connect rough-rolled portions for the sheet pile flanges to a middle section which is oblique to the rolling plane. A final Z-section sheet pile is formed from the preform in a second plurality of rolling passes.

What is claimed is: 
     
       1. A method for hot rolling a Z-section sheet pile from a semi-finished H-section product, which H-section product has a rolling plane, a web, and four flange tips, the method including the steps of: introducing said H-section product in a rolling mill train having a plurality of rotating rolls and a rolling plane parallel to the rotation axes of said rotating rolls, the web of said H-section product being parallel to said rolling planes;   performing a first plurality of rolling passes on said semi-finished H-section product to form a Z-section sheet pile preform having (a) first and second rough-rolled preforms of the lateral flanges and claws of the Z-section sheet pile to be formed,   (b) a middle section oblique to said rolling plane, and   (c) first and second flange/web transition sections connecting said middle section respectively to said first and second rough-rolled preforms of the lateral flanges and claws, said first and second flange/web transition sections being flattened so as to be substantially parallel to said rolling plane; and     performing a second plurality of rolling passes on said Z-section sheet pile preform to form a Z-section sheet pile having a plane web, two lateral flanges connected to said web, and a claw terminating each of said lateral flanges.   
     
     
       2. The method of claim 1, wherein said two flange/web transition sections and said middle section form a curved preform of the web of the said sheet pile. 
     
     
       3. The method of claim 2, wherein towards the end of said second plurality of rolling passes, said curved preform of the web is flattened to form said plane web of the sheet pile. 
     
     
       4. The method of claim 1, wherein each of said first and second flange/web transition sections of said Z-section sheet pile preform is formed to have on one side a substantially plane surface and on the other side a curved concave surface. 
     
     
       5. The method of claim 1 wherein first and second of said flange tips are opposed and third and fourth of said flange tips are opposed, and wherein during said first plurality of rolling passes: the major part of the material from opposed first and second flange tips passes into said flange/web transition sections;   the material from opposed third and fourth flange tips passes into said preforms of said lateral flanges; and   said middle section is formed almost entirely from material originating from the web of the semi-finished H-beam.   
     
     
       6. The method of claim 1, wherein said middle section connecting said two flange/web transition sections makes an angle α with the rolling plane, which angle is progressively increased up to its maximum value α(max); and in that, towards the end of the rolling process, said angle α(max) is reduced to a final value α 0 .   
     
     
       7. The method of claim 1 wherein, in a first pass of said first plurality of rolling passes, the main effect produced is a flattening of opposed first and second flange tips and a further lateral separation of opposed third and fourth flange tips. 
     
     
       8. The method of claim 1 wherein, in the formation of each of said first and second rough-rolled portions for the lateral flanges of the Z-section sheet pile, a preform of a claw, a claw/flange transition section substantially parallel to the rolling plane, and a connecting section between the claw/flange transition section and the flange/web transition section are rolled. 
     
     
       9. The method of claim 8, wherein, towards the end of said second plurality of rolling passes, said claw/flange transition section and said connecting section between said claw/flange transition section and said flange/web transition section are flattened in order to form a substantially straight flange making an angle β 0  with the rolling plane. 
     
     
       10. The method of claim 9, wherein, after having rolled the claw/flange transition section which is substantially parallel to the rolling plane, a groove is rolled in the preform of the claw in a direction perpendicular to the rolling plane. 
     
     
       11. A method for hot rolling a Z-section sheet pile from a semi-finished H-section product, which H-section product has a rolling plane, a web, and four flange tips, the method including the steps of: introducing said H-section product in a rolling mill train having a plurality of rotating rolls and a rolling plane parallel to the rotation axes of said rotating mils, the web of said H-section product being parallel to said rolling planes;   performing a first plurality of rolling passes on said semi-finished H-section product to form a Z-section sheet pile preform having (a) first and second rough-rolled preforms of the lateral flanges and claws of the Z-section sheet pile to be formed,   (b) a middle section oblique to said rolling plane, and   (c) first and second flange/web transition sections connecting said middle section respectively to said first and second rough-rolled preforms of the lateral flanges and claws, said first and second flange/web transition sections being flattened so as to be substantially parallel to said rolling plane the width of each of said flange/web transition sections substantially parallel to the rolling plane exceeding at least 15% of the final width of said plane web; and     performing a second plurality of rolling passes on said Z-section sheet pile preform to form a Z-section sheet pile having a plane web, two lateral flanges connected to said web, and a claw terminating each of said lateral flanges.